rugbyben Posted January 5, 2006 Share Posted January 5, 2006 I have found MANY possible causes and solutions for the code PO420 by searching the site, they range from o2 sensors to exaust leaks. So im trying to narrow it down for my case. can anyone who has been through this confirm a gas milage decrease before the fix? If so what was the problem? I am also getting a code P1507 Manf Cntrl Veh.Spd. Idle Speed Control Auxiliary Inputs Have any of you had this combination of codes? THANKS!!!!!! Quote Link to comment Share on other sites More sharing options...
MDW25gt Posted January 6, 2006 Share Posted January 6, 2006 I get the code PO420 on a monthly basis roughly. I just reset and go. I have a borla header and full Stromung SS exhaust including cat. Gas mpg is 22-25 in town and 28-29 on the highway. Also replaced front and back o2 sensors when I did the exhaust. Dont know if that helps. Quote Link to comment Share on other sites More sharing options...
f15xxx Posted January 7, 2006 Share Posted January 7, 2006 had this code, usually popped when lugging uphill in 5th gear. dealer replaced both cats under fed emission warranty (80k?). no more codes. original 02 sensors. it's your cats man. if your out off warranty try a boneyard.99 leg l sedan 2.2l 5m 30th anniv. Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 7, 2006 Share Posted January 7, 2006 First check for exhaust leaks. If you have no exhaust leaks then the converter/s have failed. It is very rare for an oxygen sensor to create a po420 code. It would be a good idea though to check your fuel trims. If you have access to a scan tool then post your short term and long term fuel trims from the freeze frame date. It is common on the new outbacks to have problems with their air fuel ratio sensors=front oxygen sensor. Yet the converter code is usually pretty specific to a failed converter. It should be covered under the federal emissions warranty of 8 years or 80,000 miles. So if you have less than that you get a free converter. The othe code p1507 I believe their may be a flash update. I can't check though untill Monday. Hope this helps. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 8, 2006 Share Posted January 8, 2006 That would be great if you can get it done on warranty! I suspect my cats are tired too but I know 122,000 is a bit over. Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 9, 2006 Author Share Posted January 9, 2006 Color-Blind, Please give me more information if you find it. I need a little clarification though; What are fuel trims, that is a new term to me and how do i check them also What do you mean by "Flash Update"? First check for exhaust leaks. If you have no exhaust leaks then the converter/s have failed. It is very rare for an oxygen sensor to create a po420 code. It would be a good idea though to check your fuel trims. If you have access to a scan tool then post your short term and long term fuel trims from the freeze frame date. It is common on the new outbacks to have problems with their air fuel ratio sensors=front oxygen sensor. Yet the converter code is usually pretty specific to a failed converter. It should be covered under the federal emissions warranty of 8 years or 80,000 miles. So if you have less than that you get a free converter. The othe code p1507 I believe their may be a flash update. I can't check though untill Monday. Hope this helps. Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 9, 2006 Author Share Posted January 9, 2006 I have 72K miles so I guess imunder that warranty. Do i just go to my regular mechanic, or do i need to go to a Subaru dealer to get the CATs replaced under warranty? Ill check for leaks in the intake and exaust but its difficult right now as its winter in PA and I have no garrage. Also the boxer "sound" makes it impossible to determine a leak just from listening, so i need to do the soap & water test. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 9, 2006 Share Posted January 9, 2006 Only your Subaru dealer can help you with warranty. I hope they are reasonable because it is a very old car. If they turn you down ask to talk to a district rep. Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 9, 2006 Share Posted January 9, 2006 I have found MANY possible causes and solutions for the code PO420 by searching the site, they range from o2 sensors to exaust leaks. So im trying to narrow it down for my case. can anyone who has been through this confirm a gas milage decrease before the fix? If so what was the problem? I am also getting a code P1507 Manf Cntrl Veh.Spd. Idle Speed Control Auxiliary Inputs Have any of you had this combination of codes? THANKS!!!!!! Is your vehicle an automatic or 5-spd? What year is it? How many miles are on it? Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 10, 2006 Author Share Posted January 10, 2006 5 speed, 2000 Out Back Sport, with 70,000 miles Quote Link to comment Share on other sites More sharing options...
cookie Posted January 10, 2006 Share Posted January 10, 2006 I was thinking it was earlier than that. Great, this gives you a pretty good chance! Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 10, 2006 Author Share Posted January 10, 2006 I just spoke to Bob at Stocker Subaru in State College PA. He was actually very friendly and when i described my problem he suggested the federal warranty before i even mentioned it. Here is the sticking point. To actually do the warranty work he has to determine if it is actually the cats or a bad sensor. to do that they hook a diagnostic machine up and drive the car around. Sounds great, but that is going to cost me $70.... OUCH! but if thats the only way to get them to do the warranty work what other choice do i have? Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 10, 2006 Share Posted January 10, 2006 Ok, I checked today. The p1507 their should be a flash update for the ecu, ask your local dealer. Basically they reprogram the ecu. As you now know your converters will fall under the emission warranty. $70 is pretty good for a diagnosis, I'd charge ya $80, LOL. Good luck. Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 10, 2006 Author Share Posted January 10, 2006 Thanks a lot for your help Color-Blind. I will ask them to do the update thing while im there tomorrow. Here is somthing i though i would never say. I'm praying it is the cats because that way the fix will be covered. if its somthing else then i will have to pay for it. The guy actually told me that i need to write down the repair history, i.e. when the plugs were changed because a misfire could kill the cats. i really dont think its a misfire because i would immagine there would be a code for that too. Anyways. Thanks for the help guys (& girls?) I will report back with results. Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 10, 2006 Share Posted January 10, 2006 Lets just say so far this week I've done 3 converters. It is a problem area just like the head gaskets. If anything is hurting them I'd suspect the air fuel ratio sensors. I've seen many that have codes stored for the air fuel ratio sensor and converter. I've even tried installing the air fuel ratio sensor first then reinspecting them only to find a code stored for the converters. Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 12, 2006 Author Share Posted January 12, 2006 Okay here are the results. They also got the two codes. The sensors and fuel trims all tested okay. THere was however a flash update for the computer related to the idle speed and the 1507 code. They updated the computer, and both codes were erased. The mechanic believes that it may be possible that the high idle could cause one of the sensors to react. So im just going to drive it for a while and see if the Po420 codes comes back. If it does they will replace the cats... I have 7K miles left on the federal warranty. so if its going to happen lets hope it does in the next 7,000 miles. Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 12, 2006 Share Posted January 12, 2006 Okay here are the results. They also got the two codes. The sensors and fuel trims all tested okay. THere was however a flash update for the computer related to the idle speed and the 1507 code. They updated the computer, and both codes were erased. The mechanic believes that it may be possible that the high idle could cause one of the sensors to react. So im just going to drive it for a while and see if the Po420 codes comes back. If it does they will replace the cats... I have 7K miles left on the federal warranty. so if its going to happen lets hope it does in the next 7,000 miles. Save your paperwork. The light will come back on. They should have replaced the converters. If your lucky the light will come back on soon. If not keep your paperwork as evidence. Those converters fail more often than head gaskets. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 12, 2006 Share Posted January 12, 2006 And seem to cost nearly as much. Quote Link to comment Share on other sites More sharing options...
rugbyben Posted January 13, 2006 Author Share Posted January 13, 2006 Will do. they did put it on the paperwork that if the code comes back they will replace the cats. So far it has not come back on, which is sort of a suprise because it has been off for 2 days, i ahve not had a single day where the light wasnt on since june. it would be off ocasionally but always came back on once the car heated up. Ive got my fingers crossed for the code though. because with my luck it will be the cats but the code wont come back on until a mile after the warranty is up. Quote Link to comment Share on other sites More sharing options...
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